查询词典 wavelet

The study has focused on: 1 The research background and the current state of the power measurement were analyzed systematically, and then wavelet-based power measurement algorithm was certified feasible for astable signals; 2 We developed a new method of RMS and power measurement based on Dmeyer wavelet. After that three other wavelet measurement approaches were compared with Dmeyer wavelet-based measurement approach. Then the impact on measurement errors of amplitude frequency property and energy leakage of wavelet filter banks were deeply researched, and some measures were proposed to reduce it; 3 We developed a new strategy of power measurement algorithm based on lifting wavelet, which had calculation advantage compared with the first wavelet, so that it was more suitable for the realization of hardware; 4 The running system of wavelet-based power measurement algorithm based on DSP was proposed, and then it was realized on ICETEK-VC5416-A EVM board; 5 Existing problems and the further research direction of wavelet-based power sub-band measurement algorithm was discussed.

本文对基于小波变换的功率测量算法展开深入的分析研究，主要内容有：1）系统地分析了功率分解测量的研究背景、国内外的研究现状，并从能量守恒的角度验证了小波功率分频带测量算法在非平稳信号条件下的可行性；2）首次提出了Dmeyer小波变换有效值与功率的测量方法，进而通过对该方法与3种已经提出的小波测量方法的对比分析，深入研究了小波滤波器组的幅频特性和能量泄漏特性对测量误差的影响，并针对电网谐波的特点提出了减小影响的相关措施；3）首次提出了二代小波功率测量算法，对比一代小波功率分频带测量算法，它大大减少了算法实现的运算量及内存的需求量，从而更适合于硬件的实时实现；4）提出了小波功率分频带测量算法的DSP实现方案，并在ICETEK-VC5416-A EVM板上进行了实现；5）探讨了小波功率分频带测量算法目前仍存在的问题，并提出了进一步的研究方向。

At the same time, combining with the actual condition of delivery pipeline of our country and some prevalent leak detection and location methods, this paper raised a method, which is based on wavelet analysis and negative- pressure-wave to detect and locate the leakage. Jobs in the paper are as follows:As affected by gas density, pressure, specific heat and pipe material, the velocity of negative-pressure-wave improved depending on the energy conservation. At one time, taking the affection of velocity of gas flow, the location formula was modified in some degree.When locating the leaks with location formula, the iterative approach algorithm was adopted as a new method to increase the location accuracy level of system.Multi-scale decomposition and reconstruction of wavelet transform is utilized to filter the noise of negative-pressure-wave, which was brought by leakage. With the capacity to detect the signal singularity fast and accurately, wavelet transform was used to catch the break point of pressure signal. The work improved the accuracy of At in location formula, accordingly improved the location accuracy.Wavelet is a suitable tool for signal analysis. The distinct character is that the mother-wavelet is of optional. That means choosing different mother-wavelet will get different analysis result. So we studied how to choose mother-wavelet and its scale for signal singularity detection. The method is to choose a wavelet by regularities of the wavelet and the signal.Finally, a plan, which bases on SCADA system for inspection and detection of natural gas leakage, is proposed in the article.

其中，主要进行了以下几方面的工作：针对泄漏产生的负压波在管道中的传播速度受媒介的密度、压力、比热及材质等因素的影响，而非声波在空气中传播的速度，本文利用能量守恒原理，对其进行了修正；考虑到管内气体流速对压力波速的影响，对原始的负压波定位公式进行了一定程度的改进，并在利用定位公式进行泄漏点定位时采用逐步迭代逼近算法，提高了系统的定位精度；利用小波变换的多分辨率分解和重构技术，对采集到的管道发生泄漏时产生的负压波信号进行了降噪处理；并利用小波变换技术对信号奇异点的快速、准确的识别能力，对经上述消噪后的负压波信号进行了奇异点捕捉，精确捕捉的结果提高了定位公式中上下游站点采集到的负压波奇异点的时间差△t的精度，从而进一步提高了定位的精度；考虑到小波变换是一种基波可变的信号分析工具，也就是说，不同的小波基波对信号分析的结果将有很大差别，这势必影响最终的处理结果，因此，我们又对比分析了本课题中小波基及尺度的选择问题，依据规则性系数相似性原理对母小波的选择进行了探索性研究；最后，还提出了基于SCADA的泄漏检测与定位系统的软件开发构想及系统的嵌入方案。

Audio denoising is the pre-step in the audio processing,and wavelet domain denoising has been a main research area.In order to give people a summary knowledge of wavelet domain audio denoising,based on many literatures,this paper attempts to make a survey of wavelet domain audio denoising.First,it introduces wavelet transformation and the characteristics,and gives the optimal selecting and dealing criterion of wavelet domain denoising,the basis wavelet selection.Second,describes five classical methods of audio denoising,for example,threshold,multi-wavelet,wavelet packet,modulus maximum and scale correlation,then introduces their development.Third,introduces a new algorithm based on modulus maximum and scale trading theory.At the end,the future trend of wavelet domain audio denoising is pointed out.

音频降噪是音频处理前期的必要步骤，小波域降噪是其中一个重要的研究方向，为了使人们对小波域音频降噪有概括了解，在对小波域音频降噪相关文献进行分析和理解的前提下，首先介绍了小波变换及其特性，同时阐述了小波降噪的最优选取和处理准则，及对音频进行小波变换时小波基的选取原则；然后评述了用于音频降噪的阈值，多小波、小波包、模极大值和尺度相关法等5类方法及各自的发展；接着介绍在前人基础上，提出新的基于模极大值和尺度理论的降噪算法；最后探讨了小波域音频降噪的发展方向。

By using the Ricker wavelet and thin inter-beds model data, taking Morlet wavelet, MSW wavelet (A mother wavelet which can match seismic wavelet) and three-parameters wavelet as mother wavelet respectively, the calculated instantaneous frequency is analyzed. Results show that the instantaneous frequency analysis based on three-parameter wavelet has good anti-noise ability and higher temporal resolution.

利用Ricker子波和薄互层模型数据，分析了以Morlet小波、匹配地震子波的小波及三参数小波为基本小波计算的瞬时频率，结果表明：基于三参数小波的瞬时频率分析方法具有良好的抗噪性能及较高的时间分辨率。

In order to provide the subsequent researchers with a thorough viewpoint, the writer has managed to combine the development of wavelet and make a thorough demonstration of what achievement has been made theoretically and applicably in the field of wavelet analyses, as well as the domestic and overseas situation of studying wavelet; of such major theories as multiresolution analyses, the construction of wavelet bases, the wavelet packet, and the continuous wavelet transform, of how to put the signal and image processing of wavelet in practice.

作者在阅读了国内外大量文献的基础上，结合小波的发展史全面地阐述了小波分析已经取得的理论和应用成果及其在国内外的研究现状，综述了多尺度分析、小波基的构造、小波包、连续小波变换等小波的主要理论和小波在信号和图像处理方面的应用，试图给后续研究者提供一个较全面的视角。

This paper combines with pipeline delivery of our countrys actual conditions and other methods of detection and location. To the leakage characteristic of the fault to the long-distance natural gas pipeline, a method is raised, which is on the basis of wavelet and negative-pressure-wave to detect the leakage and locate. Jobs in this paper are as follows:Multi-resolution decomposition and reconstruction of wavelet transform is utilized to filter the noises, which the leakage brings the noises of negative-pressure-wave. The research is worked in the wavelet and wavelet packet filter. The wavelet transform have a fast and accurate recognition capability to signal singularity. This paper chooses wavelet technology to catch the break point of pressure signal.

本文结合我国管道输送的实际情况和目前现有的各种泄漏检测与定位方法，针对天然气长输管线泄漏故障的特点，提出了基于小波分析和负压波相结合的方法检测泄漏并定位，其中主要进行了以下几个方面的工作：利用小波变换的多分辨率分解和重构技术，对采集到的管道发生泄漏时产生的负压波信号进行降噪处理，并对小波及小波包优化的降噪效果进行对比性研究；利用小波变换技术对信号奇异点的快速、准确的识别能力，捕捉负压波信号的突变点，从而判断是否有泄漏发生。

In chapter 4, the Newlands harmonic wavelet is improved and a new type of wavelet with better time-frequency characteristic is constructed. Frequency band of signal can be divided arbitrary with the improved harmonic wavelet so that the phenomena of aliasing are reduced. Several typical fault signals in Electromechanical System are analyzed with it. In addition to the improved harmonic wavelet in chapter 4, a new half-complex wavelet is presented to improve the complex wavelet, which is given by Chaari.O. A unilateral recursive algorithm is derived to improve the real-time characteristic. A parameter n is imported to make the time-frequency and filtering characteristics of it better and its ability of extracting fault feature is enhanced.

第四章通过对Newland谐波小波的改进构造频域紧支撑、时域性能良好的新型小波函数，可实现信号频带的任意划分，从而减少频带混叠现象，采用改进的谐波小波对多种典型的机电系统故障信号进行了分析；以Chaari.O复小波为基础构造了一个半复小波，从提高复小波算法的实时性出发，推导了半复小波单向递推算法，通过给原小波设置可调参数的方法，实现了一种能满足小波基本条件的复值小波，可以通过参数的调整调节小波滤波器在Hilbert空间的时频特性和相应的滤波性能，以加强半复小波对故障特征的提取能力。

First, the traffic flow time series chaotic feature is extracted by chaos theory. pretreatment for traffic flow time series, and the wavelet neural networks model was build by this. Second, the chaotic mechanism and the chaotic probability is described. Based on chaotic learning algorithm, and the wavelet neural networks fast learning algorithm of traffic flow time series is designed based on chaotic algorithm. Last, a single-step and multi-step prediction of traffic flow chaotic time series is researched by BP neural networks, wavelet neural networks and wavelet neural networks based on chaotic algorithm. The results showed that the wavelet neural networks predictive performance is better than the BP networks and the wavelet neural networks by the simulation results and root-mean-square value.

首先，通过混沌理论提取了交通流量时间序列的混沌特征，并在此基础上建立了小波神经网络交通流量时间序列模型；接着，阐述了混沌学习算法的混沌机理、混沌产生的概率，设计了基于混沌算法的小波神经网络交通流量混沌时间序列快速学习算法；最后利用交通流量混沌时间序列对BP网络、非混沌算法的小波神经网络以及基于混沌算法的小波神经网络进行了单步预测和多步预测，并对预测结果的仿真图和真实值与预测值的方均根进行了比较，结果表明基于混沌学习算法的小波神经网络的预测性能明显优于应用BP网络和非混沌算法的小波神经网络。

By using the Ricker wave- let and thin inter-beds model data,taking Morlet wavelet,MSW wavelet(A mother wavelet which can match seismic wavelet) and three parameters wavelet as mother wavelet respectively,the cal...

将该方法用于地下薄互层结构的地震响应分析，不仅可以刻画地层的整体变化特征，而且可以刻画薄互层内部结构。

Wavelet multi-resolution analysis is applied to decompose the signal into multiple-level and the wavelet coefficient modules of its high-frequency components are obtained. The wavelet coefficient modules of a broken signal can be extracted by software demising. The threshold of demising is decided by the difference between the wavelet coefficient modules of a broken signal and those of a noise. The wavelet coefficient modules of the broken signal were shown in different levels, then the faults can be detected and distinguished by the integrated features of the variant levels' wavelet coefficient modules.

利用小波多尺度分解技术，将信号进行多尺度的小波分解，得到不同尺度下的信号高频分量的小波系数模值，并根据奇变信号和噪声信号小波系数模值的差异，采用软阈值去噪法，对其高频分量小波系数进行去噪处理，获取不同尺度上突变信号的小波系数模值，实现对故障的检测，并可根据不同尺度上小波系数模值的对应关系，实现对多重并发故障的区分。

In the days of sailing vessels the crew were afraid they would be becalmed on the ocean.

在使用帆船的时代，船员们担心他们会因为无风而无法在海洋上航行。

As long as foreign donors pay the PA's salary bill, few expect a new intifada.

只要外国继续为巴权力机构的薪水买单，希望发动新暴动的人便寥寥无几。